The present invention relates to a probe that is used in a near field scanning microscope which is one of the scanning probe microscopes and adapted to measure the optical characteristics of a measuring substance in a fine region thereof, a probe that is used in an atomic force microscope which is also one of the scanning probe microscopes and adapted to serve the same purpose, a manufacturing method for these probes and a scanning probe microscope that uses these probes.
Scanning probe microscopes that are represented by atomic force microscopes (hereinafter referred to simply as "AFM") and scan-type tunnel microscopes (hereinafter referred to simply as "STM") have been widely used because of their enabling the observation of a fine topography of the surface of a sample. The use of the AFM enables the observation of a fine topography of a sample irrespective of whether or not this sample has conductivity compared to the STM. The measuring method of the AFM is based on the utilization of the fact that a spring element which supports a measuring probe becomes flexed by an atomic force that aces between the sample and the measuring probe.
On the other hand, there have been several attempts to measure the optical characteristics and topography of a sample by approaching a probe that consists of a optical waveguide whose tip is sharpened to a measuring sample until the distance therebetween becomes shorter than the wavelength of light, whereupon several near field optical microscopes have been proposed. As one of these microscopes there has been proposed an apparatus which horizontally vibrates the tip of the probe relative to the surface of the sample, the probe being held vertically relative thereto, detects the variation in the amplitude of the vibration that occurs due to the friction between the surface of the sample and the tip of the probe as the displacement of the optical axis of a laser light that has been radiated from the tip of the probe and has transmitted through the sample, moves the sample by a fine moving mechanism and thereby maintains the interval between the tip of the probe and the surface of the sample to be at a fixed value, and detects the surface topography of the sample from the intensity of the signal input to the rinse moving mechanism and simultaneously measures the light transmission characteristic of the sample.
Also, there has been proposed a near field scanning microscope which uses the probe that has been shaped like a hook as an AFM cantilever, vibrates the tip of the probe vertically relative to the surface of the sample, detects the variation in the amplitude of the vibration that occurs due to the action of the atomic force between the surface of the sample and the tip of the probe by the reflection of a laser light that has been radiated onto the probe, moves the sample by a fine moving mechanism and thereby maintains the interval between the tip of the probe and the surface of the sample to be at a fixed value, detects the surface topography of the sample from the intensity of the signal input to the fine moving mechanism, and simultaneously radiates a laser light from the tip of the probe onto the sample to thereby measure the optical characteristics of the sample.
In the above-mentioned scanning probe microscopes each using a probe that consists of an optical waveguide, the detection of the variation in the amplitude of the vibration occurring due to the friction between the surface of the sample and the tip of the probe, or the detection of the atomic force acting on the surface of the sample and the tip of the probe, is performed using the elastic function of the probe. Conventionally, as this elastic function, the elasticity of the optical waveguide itself is used as is.
Whereas the spring constant of the cantilever of the AFM is in a range of from 1/100 N/m to 1/10 N/m or so, the spring constant of the optical fiber is in a range of from several N/m to several ten N/m when utilizing the elastic function of the optical fiber itself. In a range wherein the near field microscopes are applied, it is considered to use a relatively large number of soft samples such as biological samples and high-molecular samples. The use of the optical fiber probe that utilizes the elastic function of the optical fiber itself with respect to these soft samples deforms these samples inconveniently. In addition, there was also the likelihood of causing damages to the tip of the probe. Further, although in the case of performing scanning control utilizing the resonance vibration of the probe the higher the resonance frequency the higher the scanning speed, when making short the elastic functioning portion that corresponds to the cantilever and thereby making the resonance frequency high, there was the problem that the spring constant thereof became further increased.
Also, where mounting the probe onto the quartz oscillator and detecting the atomic force acting between the surface of the sample and the tip of the probe or other forces associated with the interaction therebetween as the variation in the resonance characteristic of the quartz oscillator, when the spring constant and weight of the elastic functioning portion are respectively at large values, the detection sensitivity of the quartz oscillator deteriorates, with the result that here arises the problem that it is impossible to sufficiently detect weak forces such as the above-mentioned atomic forces. While in order to maintain the detection sensitivity (Q value) of the quartz oscillator it is needed to use a large quartz oscillator, there has been the problem that the spring constant becomes inconveniently large.